Kim Kwanwoo, Park Jisoo, Jo Naeun, Park Sanghoon, Yoo Hyeju, Kim Jaehong, Lee Sang Heon
Department of Oceanography, Pusan National University, Busan, South Korea.
Division of Ocean Sciences, Korea Polar Research Institute, Incheon, South Korea.
Front Microbiol. 2021 Feb 11;12:618999. doi: 10.3389/fmicb.2021.618999. eCollection 2021.
Organic carbon fixed by photosynthesis of phytoplankton during the polar growing period could be important for their survival and consumers during the long polar night. Differences in biochemical traits of phytoplankton between ice-free and polar night periods were investigated in biweekly water samples obtained at the Korean "Jang Bogo Station" located in Terra Nova Bay, Antarctica. The average concentration of total Chl- from phytoplankton dominated by micro-sized species from the entire sampling period was 0.32 μg L (SD = ± 0.88 μg L), with the highest concentration of 4.29 μg L in February and the lowest concentration of 0.01 μg L during the ice-covered polar night (April-October) in 2015. The highest protein concentration coincided with the peak Chl- concentration in February and decreased rapidly relative to the carbohydrate and lipid concentrations in the early part of polar night. Among the different biochemical components, carbohydrates were the predominant constituent, accounting for 69% (SD = ± 14%) of the total particulate organic matter (POM) during the entire study period. The carbohydrate contributions to the total POM markedly increased from 39 ± 8% during the ice-free period to 73 ± 9% during the polar night period. In comparison, while we found a significant negative correlation ( = 0.92, < 0.01) between protein contributions and carbohydrate contributions, lipid contributions did not show any particular trend with relatively small temporal variations during the entire observation period. The substantial decrease in the average weight ratio of proteins to carbohydrates from the ice-free period (mean ± SD = 1.0 ± 0.3) to the ice-covered period (mean ± SD = 0.1 ± 0.1) indicates a preferential loss of nitrogen-based proteins compared to carbohydrates during the polar night period. Overall, the average food material (FM) concentration and calorific contents of FM in this study were within the range reported previously from the Southern Ocean. The results from this study may serve as important background data for long-term monitoring of the regional and interannual variations in the physiological state and biochemical compositions of phytoplankton resulting from future climate change in Antarctica.
浮游植物在极地生长季节通过光合作用固定的有机碳，对于它们在漫长极夜期间的生存以及消费者而言可能至关重要。在位于南极特拉诺瓦湾的韩国“张保皋站”采集的双周水样中，研究了无冰期和极夜期浮游植物生化特性的差异。在整个采样期，以微型物种为主的浮游植物中总叶绿素的平均浓度为0.32微克/升（标准差=±0.88微克/升），2月份浓度最高，为4.29微克/升，2015年冰封极夜期间（4月至10月）浓度最低，为0.01微克/升。最高蛋白质浓度与2月份叶绿素浓度峰值一致，相对于极夜早期的碳水化合物和脂质浓度迅速下降。在不同的生化成分中，碳水化合物是主要成分，在整个研究期间占总颗粒有机物（POM）的69%（标准差=±14%）。碳水化合物对总POM的贡献从无冰期的39±8%显著增加到极夜期的73±9%。相比之下，虽然我们发现蛋白质贡献与碳水化合物贡献之间存在显著负相关（r = 0.92，p < 0.01），但脂质贡献在整个观测期内没有呈现任何特定趋势，时间变化相对较小。从无冰期（平均值±标准差=1.0±0.3）到冰封期（平均值±标准差=0.1±0.1），蛋白质与碳水化合物平均重量比大幅下降，这表明在极夜期间，与碳水化合物相比，含氮蛋白质优先损失。总体而言，本研究中平均食物材料（FM）浓度和FM的热量含量在先前报道的南大洋范围内。本研究结果可作为重要的背景数据，用于长期监测南极未来气候变化导致的浮游植物生理状态和生化组成的区域和年际变化。
